To message a team, you must first visit their team profile. To view all teams within your course, you can click on the "Community" tab and click on "Teams".
In this example, if we would like to message "Leading with Impact", we can simply click on their team name to visit their profile.
To contact the entire team, look for the dropdown at the top right of the team member list. You will then see the options to add new members and to "Contact team".
When selected, a conversation pop-up will display where you can add additional recipients and write your message.